None of ecosystems listed below will be identical in any two locations. Furthermore, since humans have had such a strong impact on local biota of the Marshalls, it is not really possible to separate natural ecosystems from artificial ones, although extreme examples of both should be self-evident. And in the Marshall Islands, it is not even possible to have a sharp demarcation between terrestrial and marine ecosystems.

The following list outlines the major ecosystems of the Marshall Islands. Of course, any division and figure is by nature arbitratry and should not be taken as the final word on the subject.

Ecosystem:MIXED FOREST COMMUNITYLocation: most uncultivated islandsImportance: heterogeneous mixture of many species; Neisosperma does not commonly occur; one of richest zones; pandanus trees source of food and nesting sites for reef heron, brown noddy; homefor land snails, possibly including endemics; forage grounds for birds and skinks Status: reduced from original range by human clearingThreats: land clearing; development; invasive exotics

Ecosystem:Pisonia grandis, "kañal" forestLocation: now often found only on "mo" islandsImportance: favorite roost of gregarious seabirds; birds and leaves produce rich humus; only place where jemo soil is produced; one of the most characteristic and originally widespread coral island forests Status: first forest to be cleared when planting coconutsThreats: threats; land clearing; development

Ecosystem:Tournefortia argentea, "kiden" forestLocation: all atollsImportance: one of the most successful colonists; habitat for nesting seabirds; stabilizes soil so small islands can enlarge and other species can become establishedThreats: tends to be invaded by other species

Ecosystem:Pisonia-Tournefortia "kañal"-"kiden" communityLocation: most atolls with islands undisturbed by humansImportance: dense canopy forest; old, natural; roosts and nesting sites for many birds, (fairy terns, noddies); some of the richest soil on atollsThreats: land clearing, development

Ecosystem:Neisosperma oppositifolia "kõjbar" forestLocation: most atolls with undisturbed isletsImportance: climax forest; may invade and replace mixed broadleaf forests and Pisonia forests; only pure forests found in Marshalls, although species grows throughout PacificThreats: land clearing and development

Ecosystem:Pandanus "bõb" forestLocation: location; northern atollsStatus: source of food and building materialsThreats: uncommon in Marshalls development

Ecosystem:Pemphis acidula "kõñe" scrub or scrub forestLocation: intertidal rocky areas of most atollsImportance: one of the most extreme halophytes, survives submergence by seawater; inhabits limestone with no soil at all; survives typhoons; no insects in ecosystem; extremely hard wood; aberrant form reported on Likiep and in Arno salt swamps; large specimens, 5 feet in circumference or more; very old (hundred of years), possible use in arbochronology; no undergrowth, not succeeded by any other species; habitat of long-tailed cuckooStatus: on less inhabited islands, often by inland waterwaysThreats: popularly exploited for firewood

Ecosystem:Breadfruit "mã" forest and communityLocation: all cultivated islandsImportance: major source of food for humans and animals; nesting site of endangered Micronesian pigeonThreats: urbanization; pest insects and agricultural diseases

Ecosystem:Lepturus, "ujoij" grasslands and savannahsLocation: location; Bokak and drier atollsImportance: importance; nesting site of wedge-tailed shearwater; one of earliest pioneers of bare sand and gravelStatus: stabile if left undisturbedThreats: any human activity; importation of aggressive rat species

Ecosystem:Tree holes and other small freshwater reservoirsLocation: most islandsImportance: indicate colonization patterns and patterns of dispersal of species between atolls; breeding grounds of Micronesian endemic Aedes and other insectsStatus: seasonal

Ecosystem:Bruguiera "joñ" community and basinsLocation: wetland depressions without outlets; many atolls with large islandsImportance: likely planted by early inhabitants; provide building material; cannot spread naturally since no outlet to the sea Status: very stressed or wiped out in urban areas, Majuro; protection of some recommendedThreats: filling of wetlands; urbanization; invasive exotics

Ecosystem:Sandy areas of the intertidal and subtidal zonesLocation: all atollsImportance: feeding grounds for migratory birds; habitat for many food fishes and valuable seashells; forming grounds of many components of atoll land Threats: pollution; urbanization; armorment; seawalls; dredging

Ecosystem:Sea surface; lagoon water column, open waterLocation: more than 99.99% of surface area of the Marshall IslandsImportance: plankton is extremely important to existence of the earth, more so than any other particular group of fishes or other animals or organisms; more abundant source of food than the most luxuriant forest; bacterial and organic material important many food webs; fisheries of the world bound up with plankton; decapods, euphausids, mysids, amphipods, chaetognathsThreats: over-exploitation; pollution and biological magnification

Ecosystem:Deep waterLocation: below 200 metersImportance: deep water shrimp and other commercial species; three-quarters of ocean bottom below 3,000 meters but home to less than one percent of life in sea; one of most rigorous and constant environments; "rain" of detrital particles and fecal material from upper levels supports life; biomass declines with depth; faunal diversity is extraordinarily highStatus: debatedThreats: pollution drifting down from above

_________, 1990. A Review of the Natural History of the Marshall Islands. Atoll Research Bulletin, No. 330, pp. 1-100

_________, 1992. The Coral Island Environment and its Relevance to Atoll Agriculture, pp. 45-53. in Chase, Robert. Review of Agricultural Development in the Atolls. University of the South Pacific, Apia, Western Samoa

Raynor. B., 1992. Forestry on Atolls—Past, Present, and Future, pp. 157-173 in Chase, Robert G. (ed.) A Review of Agricultural Development in the Atolls. University of the South Pacific, Apia, Western Samoa